various questions about using ansible - inventory, sharing handlers, lists and maps

[Mark Butler]

Hello team,

I am getting started with ansible but I have a number of questions.
Apologies in advance for the rather noob questions:


1. In my inventory, is there anyway I can specify a single domain for all
the hosts e.g.

[myhosts]
hostA
hostB

rather than

[myhosts]
hostA.example.com
hostB.example.com

Given the requirement that I might be run tests from outside the domain?


2. Many of my roles need to call supervisor when they have finished so they
all use the same handler:

---
- name: restart supervisor
service: name=supervisor state=restarted

However at the moment I have the same duplicated handler file for each role
- how can I avoid this and have a single handler file?


3. Is it possible to create strings from list?

I need to create a classpath variable - this is how I do it currently:

classpath: "{{ dest }}jarA.jar:{{ dest }}jarB.jar:{{ dest }}jarC.jar:{{
dest }}jarD.jar"

In Python I could use a loop to do this. Is there any way to do this in
Ansible?


4. Do map style structures exist?

Similarly, when I am getting these jars I use a list like this - ideally it
would be better to use a map, then generate the list from the map to avoid
configuration duplication. Is there any way to achieve this?

- name: my service | Get jars
action: get_url url={{ build_url }}lastSuccessfulBuild/artifact/{{ item
}} dest={{ dest }} mode=0440
with_items:
- pathA/jarA
- pathB/jarB
- pathC/jarC
- pathD/jarD


Thanks in advance,

Mark

[Michael DeHaan]

Post by Mark Butler
Hello team,
I am getting started with ansible but I have a number of questions.
1. In my inventory, is there anyway I can specify a single domain for all
the hosts e.g.
[myhosts]
hostA
hostB
rather than
[myhosts]
hostA.example.com
hostB.example.com
Given the requirement that I might be run tests from outside the domain?

There is not a way to set the domain name suffix on a group all together.

OS mechanisms on short filenames (i.e. resolv.conf) will apply

Post by Mark Butler
2. Many of my roles need to call supervisor when they have finished so
---
- name: restart supervisor
service: name=supervisor state=restarted
However at the moment I have the same duplicated handler file for each
role - how can I avoid this and have a single handler file?

Yes, you can define the handler in a common role and just use it once.

It's ok if the role doesn't have a tasks file too.

Post by Mark Butler
3. Is it possible to create strings from list?
classpath: "{{ dest }}jarA.jar:{{ dest }}jarB.jar:{{ dest }}jarC.jar:{{
dest }}jarD.jar"

Yes! See the "set_fact" module in the module docs, or just define a
variable like so anywhere else in Ansible.

Variables are lazy-evaluated at the time of use.

Post by Mark Butler
In Python I could use a loop to do this. Is there any way to do this in
Ansible?
4. Do map style structures exist?
Similarly, when I am getting these jars I use a list like this - ideally
it would be better to use a map, then generate the list from the map to
avoid configuration duplication. Is there any way to achieve this?
- name: my service | Get jars
action: get_url url={{ build_url }}lastSuccessfulBuild/artifact/{{ item
}} dest={{ dest }} mode=0440
- pathA/jarA
- pathB/jarB
- pathC/jarC
- pathD/jarD

So what you have above works.

What would be in your map/dictionary? You can definitely iterate across a
list of dictionaries and hopefully I can help explain further -- just need
a bit more context.

Thanks!

Post by Mark Butler
Thanks in advance,
Mark
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[Mark Butler]

Hi Michael,

Sorry about the SO mix-up.

The reason I don't want to define it at the inventory or group level is it
isn't associated with them - it's associated with the role - because the
service wherever it runs will use the same jars - and because the jars
often have version numbers in that will change slowly with release - so it
doesn't make sense to pass them in every time but also it makes sense to
have them in a config so they can be changed without breaking the template.

Actually, it turns out it's easy and I was being stupid because the "best
practice" document does say that I can create vars at the role level (as
Leucos pointed out, thanks!). My next question was going to be if roles can
share vars but I am guessing by your reply above they can via the common
task just like handlers.

For the list and map, this is how I would do it Python - I'm just keen to
avoid duplicate config values.

build_server_path = 'http://builderserver/path'
dest_path = '/dest/path/'
jars = {'pathA':'jarA', 'pathB': 'jarB', 'pathC': 'jarC'}

# jars have path on build server because they come from different modules
urls = [build_server_path + k + '/' + jars[k] for k in jars]

# but for service execution put them one directory and generate classpath
to simplify things
dest_jars = ['/dest/path/' + jars[k] for k in jars]
classpath = ':'.join(dest_jars)

download(urls, dest_path)
set_classpath(classpath)

Thanks,

Mark

Post by Michael DeHaan

Post by Mark Butler
Hello team,
I am getting started with ansible but I have a number of questions.
1. In my inventory, is there anyway I can specify a single domain for all
the hosts e.g.
[myhosts]
hostA
hostB
rather than
[myhosts]
hostA.example.com
hostB.example.com
Given the requirement that I might be run tests from outside the domain?

There is not a way to set the domain name suffix on a group all together.
OS mechanisms on short filenames (i.e. resolv.conf) will apply

Post by Mark Butler
2. Many of my roles need to call supervisor when they have finished so
---
- name: restart supervisor
service: name=supervisor state=restarted
However at the moment I have the same duplicated handler file for each
role - how can I avoid this and have a single handler file?

Yes, you can define the handler in a common role and just use it once.
It's ok if the role doesn't have a tasks file too.

Post by Mark Butler
3. Is it possible to create strings from list?
classpath: "{{ dest }}jarA.jar:{{ dest }}jarB.jar:{{ dest }}jarC.jar:{{
dest }}jarD.jar"

Yes! See the "set_fact" module in the module docs, or just define a
variable like so anywhere else in Ansible.
Variables are lazy-evaluated at the time of use.

Post by Mark Butler
In Python I could use a loop to do this. Is there any way to do this in
Ansible?
4. Do map style structures exist?
Similarly, when I am getting these jars I use a list like this - ideally
it would be better to use a map, then generate the list from the map to
avoid configuration duplication. Is there any way to achieve this?
- name: my service | Get jars
action: get_url url={{ build_url }}lastSuccessfulBuild/artifact/{{ item
}} dest={{ dest }} mode=0440
- pathA/jarA
- pathB/jarB
- pathC/jarC
- pathD/jarD

So what you have above works.
What would be in your map/dictionary? You can definitely iterate across
a list of dictionaries and hopefully I can help explain further -- just
need a bit more context.
Thanks!

Post by Mark Butler
Thanks in advance,
Mark
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[Mark Butler]

Hi Michael, Team,

One more question I am afraid - is there any way I can share templates
between roles?

I tried putting my template in common/templates but it didn't work?

Thanks!

Mark

Post by Mark Butler
Hi Michael,
Sorry about the SO mix-up.
The reason I don't want to define it at the inventory or group level is it
isn't associated with them - it's associated with the role - because the
service wherever it runs will use the same jars - and because the jars
often have version numbers in that will change slowly with release - so it
doesn't make sense to pass them in every time but also it makes sense to
have them in a config so they can be changed without breaking the template.
Actually, it turns out it's easy and I was being stupid because the "best
practice" document does say that I can create vars at the role level (as
Leucos pointed out, thanks!). My next question was going to be if roles can
share vars but I am guessing by your reply above they can via the common
task just like handlers.
For the list and map, this is how I would do it Python - I'm just keen to
avoid duplicate config values.
build_server_path = 'http://builderserver/path'
dest_path = '/dest/path/'
jars = {'pathA':'jarA', 'pathB': 'jarB', 'pathC': 'jarC'}
# jars have path on build server because they come from different modules
urls = [build_server_path + k + '/' + jars[k] for k in jars]
# but for service execution put them one directory and generate classpath
to simplify things
dest_jars = ['/dest/path/' + jars[k] for k in jars]
classpath = ':'.join(dest_jars)
download(urls, dest_path)
set_classpath(classpath)
Thanks,
Mark

Post by Michael DeHaan

Post by Mark Butler
Hello team,
I am getting started with ansible but I have a number of questions.
1. In my inventory, is there anyway I can specify a single domain for
all the hosts e.g.
[myhosts]
hostA
hostB
rather than
[myhosts]
hostA.example.com
hostB.example.com
Given the requirement that I might be run tests from outside the domain?

There is not a way to set the domain name suffix on a group all together.
OS mechanisms on short filenames (i.e. resolv.conf) will apply

Post by Mark Butler
2. Many of my roles need to call supervisor when they have finished so
---
- name: restart supervisor
service: name=supervisor state=restarted
However at the moment I have the same duplicated handler file for each
role - how can I avoid this and have a single handler file?

Yes, you can define the handler in a common role and just use it once.
It's ok if the role doesn't have a tasks file too.

Post by Mark Butler
3. Is it possible to create strings from list?
classpath: "{{ dest }}jarA.jar:{{ dest }}jarB.jar:{{ dest }}jarC.jar:{{
dest }}jarD.jar"

Yes! See the "set_fact" module in the module docs, or just define a
variable like so anywhere else in Ansible.
Variables are lazy-evaluated at the time of use.

Post by Mark Butler
In Python I could use a loop to do this. Is there any way to do this in
Ansible?
4. Do map style structures exist?
Similarly, when I am getting these jars I use a list like this - ideally
it would be better to use a map, then generate the list from the map to
avoid configuration duplication. Is there any way to achieve this?
- name: my service | Get jars
action: get_url url={{ build_url }}lastSuccessfulBuild/artifact/{{
item }} dest={{ dest }} mode=0440
- pathA/jarA
- pathB/jarB
- pathC/jarC
- pathD/jarD

So what you have above works.
What would be in your map/dictionary? You can definitely iterate across
a list of dictionaries and hopefully I can help explain further -- just
need a bit more context.
Thanks!

Post by Mark Butler
Thanks in advance,
Mark
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[Michael DeHaan]

You can ../../common/templates/foo.j2 in the src=

-- Michael

On Feb 24, 2014, at 6:44 PM, Mark Butler <***@gmail.com> wrote:

Hi Michael, Team,

One more question I am afraid - is there any way I can share templates
between roles?

I tried putting my template in common/templates but it didn't work?

Thanks!

Mark

Post by Mark Butler
Hi Michael,
Sorry about the SO mix-up.
The reason I don't want to define it at the inventory or group level is it
isn't associated with them - it's associated with the role - because the
service wherever it runs will use the same jars - and because the jars
often have version numbers in that will change slowly with release - so it
doesn't make sense to pass them in every time but also it makes sense to
have them in a config so they can be changed without breaking the template.
Actually, it turns out it's easy and I was being stupid because the "best
practice" document does say that I can create vars at the role level (as
Leucos pointed out, thanks!). My next question was going to be if roles can
share vars but I am guessing by your reply above they can via the common
task just like handlers.
For the list and map, this is how I would do it Python - I'm just keen to
avoid duplicate config values.
build_server_path = 'http://builderserver/path'
dest_path = '/dest/path/'
jars = {'pathA':'jarA', 'pathB': 'jarB', 'pathC': 'jarC'}
# jars have path on build server because they come from different modules
urls = [build_server_path + k + '/' + jars[k] for k in jars]
# but for service execution put them one directory and generate classpath
to simplify things
dest_jars = ['/dest/path/' + jars[k] for k in jars]
classpath = ':'.join(dest_jars)
download(urls, dest_path)
set_classpath(classpath)
Thanks,
Mark

Post by Michael DeHaan

Post by Mark Butler
Hello team,
I am getting started with ansible but I have a number of questions.
1. In my inventory, is there anyway I can specify a single domain for
all the hosts e.g.
[myhosts]
hostA
hostB
rather than
[myhosts]
hostA.example.com
hostB.example.com
Given the requirement that I might be run tests from outside the domain?

There is not a way to set the domain name suffix on a group all together.
OS mechanisms on short filenames (i.e. resolv.conf) will apply

Post by Mark Butler
2. Many of my roles need to call supervisor when they have finished so
---
- name: restart supervisor
service: name=supervisor state=restarted
However at the moment I have the same duplicated handler file for each
role - how can I avoid this and have a single handler file?

Yes, you can define the handler in a common role and just use it once.
It's ok if the role doesn't have a tasks file too.

Post by Mark Butler
3. Is it possible to create strings from list?
classpath: "{{ dest }}jarA.jar:{{ dest }}jarB.jar:{{ dest }}jarC.jar:{{
dest }}jarD.jar"

Yes! See the "set_fact" module in the module docs, or just define a
variable like so anywhere else in Ansible.
Variables are lazy-evaluated at the time of use.

Post by Mark Butler
In Python I could use a loop to do this. Is there any way to do this in
Ansible?
4. Do map style structures exist?
Similarly, when I am getting these jars I use a list like this - ideally
it would be better to use a map, then generate the list from the map to
avoid configuration duplication. Is there any way to achieve this?
- name: my service | Get jars
action: get_url url={{ build_url }}lastSuccessfulBuild/artifact/{{
item }} dest={{ dest }} mode=0440
- pathA/jarA
- pathB/jarB
- pathC/jarC
- pathD/jarD

So what you have above works.
What would be in your map/dictionary? You can definitely iterate across
a list of dictionaries and hopefully I can help explain further -- just
need a bit more context.
Thanks!

Post by Mark Butler
Thanks in advance,
Mark
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[Alexander Litnitskiy]

Regarding first question I do it myself like:

[myhosts]
hostA
hostB

group_vars/all
ansible_ssh_host: "{{inventory_hostname}}.{{domain}}"

group_vars/myhosts:
domain: example.com

In my case each group/host must define "domain" variable.

Post by Mark Butler
Hello team,
I am getting started with ansible but I have a number of questions.
1. In my inventory, is there anyway I can specify a single domain for all
the hosts e.g.
[myhosts]
hostA
hostB
rather than
[myhosts]
hostA.example.com
hostB.example.com
Given the requirement that I might be run tests from outside the domain?
2. Many of my roles need to call supervisor when they have finished so
---
- name: restart supervisor
service: name=supervisor state=restarted
However at the moment I have the same duplicated handler file for each
role - how can I avoid this and have a single handler file?
3. Is it possible to create strings from list?
classpath: "{{ dest }}jarA.jar:{{ dest }}jarB.jar:{{ dest }}jarC.jar:{{
dest }}jarD.jar"
In Python I could use a loop to do this. Is there any way to do this in
Ansible?
4. Do map style structures exist?
Similarly, when I am getting these jars I use a list like this - ideally
it would be better to use a map, then generate the list from the map to
avoid configuration duplication. Is there any way to achieve this?
- name: my service | Get jars
action: get_url url={{ build_url }}lastSuccessfulBuild/artifact/{{ item
}} dest={{ dest }} mode=0440
- pathA/jarA
- pathB/jarB
- pathC/jarC
- pathD/jarD
Thanks in advance,
Mark